Modified rosin esters



Patented Apr. 25, 1950 MODIFIED ROSIN E STERS Ray V. Lawrence and Muriel W. Kaufmann, New Orleans, La., ass'ignors to the United States of 7 America as represented by the Secretary oi.

Agriculture No Drawing. Application May 24, 1946, Serial No. 672,045

(Granted under the act of March 3, 1883, as amended April so, 1928; 370 o. G. 757) 2 Claims.

This application is made under the act of March 3, 1883, as amended by the act of April 30, 1928, and the invention herein described, if patented, may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment to us of any royalty thereon.

This invention relates to a new composition of matter, a synthetic resin, and a method for producing it. The resin consists essentially of a modified rosin ester which is prepared by esteriiying the reaction product of rosin and lactic acid with an alcohol. This resin has characteristics which make it valuable for use in varnishes, printing inks, and lacquers, and also as a plasticizer for other resins and in synthetic rubber.

We have found that when rosin and lactic acid are heated together at, for example, 250 to 260 C. for from 30 minutes to 2 hours, a product is formed which has a lower acid number than either of the original products. Thus, when rosin product having an acid number of 137 to 145 is formed, whereas, theoretically, such a mixture should have an acid number of approximately 270.

. xylitol, mannitol, sorbitol, pentaerythritol, tri- The properties of this resin may be varied by varying the amount of lactic acidadded to the rosin and by varying the amount and type of alcohol used for esterification. The product obtained by heating rosin which contains from 2 to In general, as the lactic acid content of the resin is increased the rate at which the product will react with an alcohol is increased." Thus, at 250 C., rosin and 2,3 butylene glycol will reach an'acid number of '78 in 5 hours; if 2 percent lactic acid is added to the rosin, an acid number of 67 is reached in 5 hours; and when rosin containing 22 percent lactic acid is used under the same conditions, an acid number of approximately 25 is obmined in 5 hours. In generahin per!" centages of lactic acid tend to produce decreasing brittleness in the finished ester.

The reaction between rosin and lactic acid may be .carried out at temperaturesbetween 220 C.

and 290 C., for example, and ma be continued for from 15 minutes to 5 hours? Thus, it was found that, when rosin containing 22 percent lactic acid was heated at 225 C. for 5 hours, a

product having an acid number of 143' was formed, and when the resulting product was 2 heated with 2,3 butylene glycol for 5 hours at 225 C., it yielded a modified ester having an acid number of 13. At temperatures of 260 C., and above, a reaction time of minutes was satisfactory for the reaction between rosin and lactic aci In order to obtain a reasonably rapid rate of reaction between rosin and an alcohol, it is usually necessary to carry out the reaction at temperatures of 250 C. and above. The use of temperatures above 250 C. is often inconvenient because of the low boiling point of the desired alcohol. It has now been found that, if the rosin is first caused to react with 2 to 40 percent of its weight of lactic acid at, for example, approximately 260 C., the product so formed will react with alcohols at a satisfactory rate at temperatures as low as 200 to 225 C.

The alcohols used may be monohydric alcohols such as, for example, octyl, lauryl, stearyl or operable equivalents thereof; or they may be aliphatic glycols such as, for example, ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, triethylene glycol or operable equivalents thereof; or they may be polyhydric alcohols such as, for example, glycerol, diglycerol,

methylol propane or operable equivalents thereof.

The rosin used in the preparation of these products may be gum rosin, wood rosin, or'hydrogenated rosin; orit may be a stabilized rosin of the type described as United States Patent between lactic acid and rosin is not known.

The following examples will serve to illustrate our invention, but they are not to be considered as limiting it to these particular components, proportions, or conditions of reaction.

EXAMPLE I One hundred fifty parts by weight of WWgum rosin were heated to 250 C. and held at this temperature while parts by weight of percent lactic acid was added over a period of 2 /2 hours.

Thirty minutes after all of the lactic acid had been added, 16 parts by weight of glycerol was added during a period of 6 minutes. .The rehours.

" period of 2 hours.

aunt o.

action with the glycerol was continued for 4 hours at 250 C. At the end of this time, the product had an acid numberof 5.9 and a melting point' lring and ball) of 74.5 0.

EXAIWPLE II Six samples of 150 parts by weight of rosin each d Table I imc n i F Rosin, Parts by weight 150 150150 150 T50 1'50 Lactic Acid (85%), Parts by E weight one 3 10 2O 30 50 2, 3 Butylene Gl s" lay weight. '33 31 1 2e *"26 Temperature on, V v A g O; 250 250' 250 260 260 260 Reaction Ti-ma-Hoursfleflu l l0 5% 4% '-4% 3 6 "AcidfNumber of Product 55 "32 35 32.3 26.7- 31.3 -Meltin'gPoin't, *Q-(ringand -ba1l 78 65 73 67 70 59 "'Color'Giade M K M N N WG :It will be .seen 'fromTable Ithat the product formed, whenro sin and lactic acid react atapproximately 250- C., reacts much more rapidly withltheflfi but'ylene glycol than doesrosin alone.

1. V EXAMPLE'III T Twosaniples oi rosin',- 150-parts by weight each, i were heated with 3 parts and 10 parts by weight f-0f lactic acid, respectively, at- 290" CJfOI SI-ightIY wless-than minutes, Fifteen parts by weight of glycerol was then added to the ros-in-lactic acid.

' product, and the temperature was held at 290 C."'Eor-comparison', 150 parts by weight of rosin, was'esterified with 15 parts .Lby weightbtglyceroL at 290C. The results are shown .in Tab'I'e II.

These results show that when rosin is'reacted with-lactic acid prior to esterific'ation, the ester gum produced has a loweracid number than is 7 obtained under the same conditions in the absence 'of thelactic acid.

EXAMPLE'IV Onehundred fiftyparts'by'weight of rosin and 50 parts .by weight of .85 percent lacticjacid were he'a't'ed'together at atemperature of 250 C. for 3 mannitol had been added, making a total esteri-- fication time of '8 hours. The product formed 5 mu: an" acid a number of- 23.0 arid-"a melting point- EXAMPLE V one hundred fifty parts by weight ofrosin'and'i 24 pa'rtsby' weight of 85 percent lactic acid were h'eated tof260 C. and held "at this temperature;

' tor "minutes, 'afterwhich timez i arts by At this time, theaddition of 21 grams of ni'annitol 'was's'tarted andwas continued for a The esterifi'cation was continued at"250 C. for 5 hoursafter'all' of the'" weight of 1,2-propylene glycol was added slowly over a period of 2 hours. This run was repeated at the sametemperature, iusing the same amounts of rosirran'd propylenegIycoLbut no'lactic acid.

5 The results are given in the following table.

Table III :Bosi 'Ba ebywe sht Lactic Acid.(8 5.%), Parts by weight.

1,2-Propylene' Glycol,'-' Parts by weig 24 24 Temperature of Reaction, "0 260 260 e'actio'n' Time,"Hours i 5 5 --:Acid Number 36. 9 7. 3

. a he ru With lactic acid (B) shows a very much -';:Iower acid mumb'er than the control run (A);

- EXAMPLE'VII f One hundred fifty.'partslbyweight. ofl hydro- .of lactic acid"for1"30"minutes"at260 C. At the $5 end of this tim'efldfparts by weightof'jglycerol was added and the temperature "held .at11260" C.

ifor' (i-hours. 'Th'eesterTformed h'ad' an acid number of'and a mlting'ipoint' (ring and ball) 'One*huntired-fifty parts byweightof rosin was heated with 48wparts by weight of "85 *percent 5 lactic acid for =-30':m1'nutes 'at 260 C. After this reaction-period -16 parts ,:by "weight of pentaerythritolwvas added. Thertemperature was zrriaintained: at QGO Ci forifi hours :andrfi fminutes after the addition' of the zpentaerythritol. At

"this time, the*reaction product hadlan'racid number of-9.5 and a-ni'elti'ng point "(ring-sand ball) of 'fifi'flheated together 'for hours at 225 C. "lTheacid number of -the;product formedwas 143, and the temperature washeld atT225-.C.,-and 50' parts by weight. of 2,3butylen'e' fgl ycol was add'ed over a i 'In .-summary, the-,pro.ces's comprises'lheating an acid subs'tance'of' the group consisting of rosins and abietic"acidwithfioin'2'to"40 percent of its weight of lactic acid at a" temperature" between about 15 'mini'ites to 5 hoursy'andh'eating the 'rodii'ctiso i'formedj with an alcoholat' between abbut 200 andf'29'0 C'." f or a "periodfoifroni about *Havi'ng 7 thus fdescribedour' invention, we claim '1. A pro'cessffor preparing a syntheticfresin,

' comprising heating 'ros'imwith' lactic acid in the ratio oi onelhundredandfifty 'parts'tof rosin to '15 about'40.8*parts"of laetidacid for 'abblitlifl 'min- 5 utes at about 260 0., and heating the product with about 16 parts of pentaerythritol at about 260 C. for about six hours and forty-five minutes.

2. The product prepared by the process of claim 1, having an acid number of 9.5 and a 5 melting point of about 110.5 C.

RAY V. LAWRENCE. MURIEL W. KAUFMANN.

REFERENCES CITED 10 The following references are of record in the file of this patent:

Paint and Varnish Production Manager, vol. 10, February 1934, page 24. 

1. A PROCESS FOR PREPARING A SYNTHETIC RESIN, COMPRISING HEATING ROSIN WITH LACTIC ACID IN THE RATIO OF ONE HUNDRED AND FIFTY PARTS OF ROSIN TO ABOUT 40.8 PARTS OF LACTIC ACID FOR ABOUT 30 MINUTES AT ABOUT 260*C., AND HEATING THE PRODUCT WITH ABOUT 16 PARTS OF PENTAERYTHRITOL AT ABOUT 260*C. FOR ABOUT SIX HOURS AND FORTY-FIVE MINUTES. 